During the 1980s and early 90s a lot of companies offered 1911 build kits. Most used cheap cast frames and slides from Federal Ordnance, Ranger, and Essex. Springfield Armory was probably the first company to offer a kit using decent components, and most of their parts were still drop-in. Unfortunately these days nobody wants to put together a "mil-spec" 1911 with relaxed clearances that you can build in an afternoon. As a result everything is oversized and requires fitting.